Steel containing tellurium



Reiasued Feb. 1 0, 1 942 UNITED STATES PATENT oFFlcE STEEL conra ri rilll o. TELLURIUM Morgan 1. a.

Morris, Massillon, Ohio, assignor to Republic Steel Corporation,

Cleveland, Ohio, a

corporation of New Jersey No Drawing. Original No. 2,236,710, datedApril 1, 1941, Serial No. 353,891, August 23, 1940.

Application forreissue November 5, 1941, Se-

rial No. 417,942

2 Claims.

This invention relates to the art of making steel and is particularlyconcerned with a new a and improved method of making fine grained,abnormal steels and with the resulting product.

; Since about 1922 steels have been classified as normal or abnormal,depending upon the exconsiderable dlmculty in tent to which the grainsare surrounded by the grain boundary material, 1. e., cementite after adefinite carburizing operation is performed. When the grain boundarymaterial is well defined and substantially continuous around each grainthe steel is said to be normal, but when the grain boundary material isnot substantially continuous the steel is said to be abnormal, and thedegree of abnormality depends upon the extent to which the boundarymaterial is interrupted. A steel is classified in the trade as normal orgrade A steel when it has asubstantially continuous boundary ofcementitearound each grain. Abnormal steels are classified in the trade(Dodge test) in grades B, C and D. In grade B the boundary material isslightly broken; in grade C it is considerably broken; and in grade D itis more or less limited to one or possibly two sides of the grain andhas an appearance which is often referred to as "grape bunches.

For approximately the same length of time the steel industry hasclassified the sizes of grains in steel accordin to the standard chartof 'the American Society for Testing Materials. This chart extends fromnumber 1 for very coarse,

grains to number 8 for very fine grains.

The present invention has to do particularly with abnormal steelsv whichare classifiable in grades B, C

or D (Dodge test) which have grains ranging in size between about #5 andabout #8 on the A. S. T. M. standard scale, and which have compositionswithin the following ranges:

The Wills Patent No. 1,992,905, issued February 26, 1935,- disclosessteels of particular composltionsand" characteristics and also disclosesa process for making these steels. The patent states that theabnormality is induced by converthan I have been able General rangePreferred range Percent Percent 99.27 i090. .90 to94.37 .15 to 2.0 .15to 1.25 .30 to.3.0 .50 to 1.5 ,.20 to 1.5 .20 to .70 .15 to 2.5 .15 to2.0 .01 to .4 .02 to .06 Phosphorus .01 to .05 .01 to .04 Tellurium.005to .10 .005to 05,

. treme dispersion of such sion of the aluminum into alumina and theexalumina,

Wills type I have had controlling the grain size and abnormality of suchsteels by the use of aluminum. The retarding effect of the alumina onthe solubility of the carbides seemed not to be consistent with theresult that grain sizes and abnormalities of various heats variedconsiderably, I have obtained similar results with other retarders ofthe solubility or carbides. Moreover, none of these retarders producedthe maximum desired degree of In making steels of the In the steels ofthe Wills type the core grains exhibited tendencies to coarsen attemperatures well below about 1700 F.

The present invention provides a steel of the Wills typelin which theabnormality and grain size may be controlled to a much greater extent tocontrol them heretoof steels of the present fore. The abnormalityinvention may be more orless consistently maintained in the grade D(Dodge test) and are always classifiable at least in grade B. The grainsizes in the outer portions may be more or less consistently maintainedat about #7 or #8 on the A. S. T. M. standard scale but all such grainsare no larger than #5, and the core grains do not coarsen' materially attemperatures materially below 1700 F.

Briefly stated, the present method includes the introduction of smallamounts of tellurium into molten metal of the Wills type. Preferably thetellurium is added in the form of small pellets and may be added to themetal in the ladle or while the metal is being poured into ingot molds.The amount of tellurium added may vary within a fairly wide range, forexample, from about 20 gms. (avoirdupois) to about twopounds per ton ofsteel. Satisfactory results have been obtained with about 25 gms. oftellurium per ton of steel and also with about one pound of telluriumper ton of steel. When the amounts of tel 'lurium rangefrom about 25ems. to about one pound per ton of steel, their correspondingpercentages are from about.005% to about .05%.

The present invention may be readily practiced by steel makers. Steel ofthe" Wills type is made according to regular standard practice and astaught by the Wills patent. and the tel- I lurium may be added asjust'described.

\ Articles made from such steels produced by the present method havesubstantially the same physical properties as those stated in the Willsabnormality nor the desired resistance to coarsening of the core grains.

slstance to core grain coarsening at temperatures below about 1700' P. 7

Having thus described the present invention so that those skilled in theart. may be able to understand and practice the same, I state that whatpatent with the additional property of high reabout 3.00% 01' V mainderbeing carbon. between about 30% and manganese. between about .15% andabout 2.50% 01 silicon, between about 20% and about 1.5% 01' molybdenum,and between about .005% and about .10% of tellurium, the remainder beingsubstantially all iron with small amounts of sulphur and phosphorus.

2. An alloy steel containing between about .6 to .7% or carbon, betweenabout .7 to .9% of manganese, between about .2 to .3% of silicon,between about .2 to .3% of molybdenum, and between about .005 to .1% oftellurium, the resubstantially all iron with small amounts of sulphurand phosphorus.

MORGAN J. R. Momus'.

about 2.0% of

